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Press Release, March 16, 2017
dr. christiane menzfeld
tel.: +49 89 8578-2824
[email protected]
www.biochem.mpg.de/news
Operation of ancient biological clock uncovered
A team of Dutch and German researchers under the leadership of Albert Heck and Friedrich
Förster has discovered the operation of one of the oldest biological clocks in the world, which is
crucial for life on earth as we know it. The researcher from the Max Planck Institute of
Biochemistry and the Utrecht University applied a new combination of cutting-edge research
techniques. They discovered how the biological clock in cyanobacteria works in detail. Important
to understand life, because cyanobacteria were the first organisms on earth producing oxygen via
photosynthesis. The results of their research were published in Science.
Ten years ago, researchers discovered that the biological clock in cyanobacteria consists of only
three protein components: KaiA, KaiB and KaiC. These are the building blocks - the gears, springs
and balances - of an ingenious system resembling a precision Swiss timepiece. In 2005, Japanese
scientists published an article in Science showing that a solution of these three components in a test
tube could run a 24-hour cycle for days when a bit of energy was added. However, the scientists
were not able to uncover the exact operation of the system, despite its relative simplicity.
William Faulkner
How could the scientists resolve the working of the individual pieces? “In the end, the trick to
understand the ticking biological clock in cyanobacteria was to literally make time stop”, tells
research leader Albert Heck from Utrecht University. “Or as William Faulkner, Nobel Prize Laureate
in Literature said: ‘Only when the clock stops does time come to life.’ Faulkner spoke taking a pause
in the constant haste of life. That was also the trick here. We slowed the biological clock by running
it in the fridge for a week. In the literal sense we have frozen the time.”
New combination
In addition to stopping time, the researchers applied a new combination of cutting-edge research
techniques. With one technique, they were able to determine how often each of the three protein
complexes - KaiA, KaiB and KaiC - assembled or disassembled in a single 24-hour cycle. This taught
them which collections of protein components - combinations of gears, springs and balances determine the daily rhythm.
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Zooming in
They then stopped the clock at specific moments by reducing the temperature. This allowed them
to use a variety of techniques to zoom in in great detail on the structure of the collection of protein
components at that moment - the position of the gears, springs and balances. In so doing, they
identified the two structures that are vital to understanding how the clock works. The researchers
could then derive how the wheels turn by determining the transitions from one structure to
another. This produced a model that shows exactly how only three protein components form a
precision timepiece that operates on a 24-hour cycle.
"Even though the biological clock of cyanobacteria is very old in terms of geological history, we can
still learn a lot from the system today," says Heck. Just a few years ago researchers discovered a
similar process in our red blood cells. "Cyanobacteria are the first organisms that have produced
oxygen. Oxygen enrichment was the foundation for today's life. With the results of this study, we
are learning about the biological primal mechanisms of life, but we can pursue specific aspects
directly in clinical research," Heck summarizes.
Caption
Stopping the clock to understand its mechanics. At ambient temperature, the circadian clock of
cyanobacteria is constantly ticking and its “molecular cogwheels” keep spinning. This makes it
difficult to understand the clockwork mechanism. Cooling down the clock puts its cogwheels to
rest, allowing to visualize details of their appearance and assembly.
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Original publication:
J. Snijder, J.M. Schuller, A. Wiegard, P. Lössl, N. Schmelling, I.M.Axmann, J.M. Plitzko, F. Förster
and A.J.R. Heck: Structures of the cyanobacterial circadian oscillator frozen in a fully assembled
state, Science, March 2017
Contact:
Prof. Dr. Jürgen Plitzko
Department Structural Biology
Max-Planck-Institut für Biochemie
Am Klopferspitz 18
82152 Martinsried
E-Mail: [email protected]
www.biochem.mpg.de/baumeister
Dr. Christiane Menzfeld
Public Relations
Max Planck Institute of Biochemistry
Am Klopferspitz 18
82152 Martinsried
Germany
Tel. +49 89 8578-2824
E-Mail: [email protected]
www.biochem.mpg.de